Generally, a data center consists of an equipment room, utilities, and support infrastructure including for example, air cooling or handling equipment and associated electrical and data cable. Industry accepted recommendations for the protection of data centers are provided in FM Global publication “Property Loss Prevention Data Sheet 5-32: Data Centers and Related Facilities” (July 2012). The loss prevention recommendations include protection recommendations for data centers using water mist systems. More specifically, Data Sheet 5-32 provides data center protection recommendations using an automatic water mist system FM Approved for protection of light hazard occupancies. According to the FM recommendations, use of the water mist systems is subject to certain restrictions or limitations including: (i) the water mist system must be a wet system, i.e., a system in which the automatic nozzles are attached to a piping system containing water and connected to a supply so that water discharges immediately from nozzle operated by the heat from a fire; (ii) the data center to be protected must use non-fire-propagating cables in its cable trays; and (iii) the ventilation or air handling systems of the data center are to be interlocked with the water mist system to shut down upon actuation of the water mist fire protection system.
For data center operations it is desirable to run its ventilation systems independent of or without the restrictions of fire protection. Data center equipment rooms can be very large having square footage equal to one or more football fields. For such data centers, shutting down the ventilation system upon fire protection system operation can be an impediment to the data center operations particularly where any indication of a fire is limited to a small area. Accordingly, it would be desirable to have water mist fire protection systems for data centers in which the ventilation or cooling systems can provide for continuous cooling during fire protection operation. Additionally, it would be desirable to have water mist fire protection for propagating and non-propagating cable to provide additional flexibility in the data center construction and operation. Moreover, it would be desirable to have water mist fire protection for a data center that can be configured as a dry pipe or preaction system to keep water out of the system piping in an unactuated state of the water mist system.
Criteria for FM Approval of water mist systems is provided in FM Approvals LLC publication “Approval Standard for Water Mist Systems: Class Number 5560” (November 2012). In October 2014, FM Approvals made a conference paper presentation at the International Water Mist Association (IWMA) Conference in Istanbul, Turkey entitled “Planned Updates to FM Approval Standard Class 5560, Water Mist Systems, for 2015 Revision.” In the presentation, it was noted that the Class 5560 Approval Standard does not evaluate the aforementioned Data Sheet 5-32 restrictions. Accordingly, FM Approval set forth in its presentation the objectives for evaluating water mist systems in data center protection: i) to evaluate specific fire load, e.g., cables for data processing equipment room; (ii) to evaluate forced ventilation; and (iii) to evaluate water delivery time delay including interlocked systems. The IWMA presentation outlined fire test protocols and criteria for the protection of data centers for above and below a raised floor without the recommendation restrictions. A copy of the FM Approval conference paper is available at <http://iwma.net/fileadmin/user_upload/IWMC_2014/FM_Carpenter_Jon_IWMC_2014.pdf.
Accordingly in 2014, work was ongoing to enable fire testing of water mist systems for data centers without the FM recommendation restrictions. However, the 2014 conference paper does not identify specific nozzles for use in the proposed fire testing, it does not identify specific nozzle spacing or operational parameters, nor does the paper outline the manner in which nozzles can be identified for use the proposed fire test or in an actual data center environment without the system restrictions. At that time, there remained a need for a system solution which identified nozzles and their installation parameters to overcome the system restrictions of Data Sheet 5-32.